> So, in your mind how many SIR prefixes will be used in a 
typical T1 operator domain?

Sri, very good question and I don't think anybody figured this yet for 5G..

                > Also, how can we quantify the state that ILA introduces in 
different parts of the network?

                Please look at topology of section 2 in

                https://tools.ietf.org/html/draft-herbert-ila-ilamp-00. ILA 
routers collectively contain the all the mappings for the domain. The mappings 
can be sharded on the routers serving a shard can be replicated. There are two 
cases where ILA transformation is needed: at netwrok ingress (e.g. from 
Internet) and intra domain traffic. The first case                 is served by 
edge routers which as I mentioned would have considerable load. For intra 
domain communications routers would be used aslo, but they can be augment by 
the use of mapping caches in forwarding nodes.

                Forwarding nodes perform ILA to SIR transformation before 
delivery-- this does not need a lot of state.

                Presumably every mobile node in the network has an identifier 
to locator mapping. So the number of mappings in the domain equals the number 
of  mobile nodes. This number is expected to reach into the the billions, a 
scale a single device won't have the memory for the full mapping table so it 
would be sharded. Each shard also would   be replicated N ways. So number of 
routers needed is num_shards * num_replicas.

                Another major consideration for scaling is changes to the 
mapping system. It's a little harder to quantify since the load on the system 
depends on the rate at which mobile nodes are moving. I'm not sure what the 
rate of device moving in cellular network is (someone might have good insights 
on that), but for scaling estimates I'm using 1              % (that is at an 
given time 1% of devices are moving to different eNb).

Tom, 1% seems to be incorrect assumption even for 4G and also regardless of how 
you partition shreds I see potential for massive state introduced in the core 
(in various nodes); and I am not even sure how "making anchorless"  solution is 
 the most important/pressing goal.


Uma C.
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